1. Field of Invention
The present invention relates to a bulb, and more particularly to a light emitting diode bulb.
2. Description of Related Art
Light emitting diodes (LEDs) have advantages of small size, low driving voltage, long service life and environmental protection. Therefore, light emitting diode bulbs (LED bulbs) have gradually replaced conventional tungsten bulbs and have been used widely. The LED bulbs are typically divided into two types, which are semi-directional LED bulbs and omni-directional LED bulbs. The difference between the semi-directional LED bulbs and the omni-directional LED bulbs are light-emitting angles. The light-emitting angles of the semi-directional LED bulbs are about 100 degrees, and the light-emitting angles of the omni-directional LED bulbs are about 200 degrees. Therefore, the LED bulbs with different light-emitting angles can be applied on various occasions according to requirements.
However, some LED bulbs only have one single light-emitting angle, for example, omni-directional or semi-directional light-emitting angle. For users, if different light-emitting angles are required in one occasion, the users have to pay doubled price to buy the two types of the LED bulbs with different functions for replacement. For manufacturers, methods for manufacturing LED bulbs having two different functions are different, and the manufacturers have to separately manufacture the LED bulbs having the different functions, thus increasing the production cost. For sellers, the sellers have to sell the two types of the LED bulbs having the different functions to meet market requirements, which is disadvantageous to controlling selling cost.